The verse doesn't just say 'love your wife,' it says to love her 'as your own body.' What's the radical difference?
Paul calls husbands to a love that's more than just tender feelings; it's about deep identification. Think of it this way:
One Flesh, One Self
Because a husband and wife are 'one flesh' (a concept Paul roots in Genesis 2:24, which he quotes later in the chapter), they are intrinsically linked. The wife isn't just like his body; she is his body in a profound, marital sense. This means her well-being, her comfort, her needs are to be considered as if they were his own.
The Analogy of Self-Love
Paul uses the universal truth of self-love as the benchmark. Just as no one hates their own body but nourishes and cares for it, a husband should do the same for his wife. He takes care of himself because his own welfare matters. In marriage, a husband's welfare is inseparable from his wife's. Loving her is loving himself, because her flourishing directly impacts his own.